UNITED NATIONS (Reuters) - The United Nations Security Council is due to vote on Friday on a Japanese-drafted resolution to renew for one month an international inquiry into chemical weapons attacks in Syria, but diplomats said Russia opposed the measure.

It was not clear if Russia would cast its second veto in as many days or abstain. Russian U.N. Ambassador Vassily Nebenzia was not immediately available to comment.

Russia vetoed on Thursday a U.S.-drafted resolution to renew the joint inquiry by the U.N. and the Organization for the Prohibition of Chemical Weapons (OPCW), which found that the Syrian government used the banned nerve agent sarin in an April 4 attack. The inquiry's mandate expires on Friday.

French U.N. Ambassador Francois Delattre said on the Japanese draft resolution: "This is a way to avoid the death of the JIM (Joint Investigative Mechanism)."

"This is a way to give us time ... to work hard and to try to find the spirit of unity that is absolutely needed, when the very future of the non-proliferation regime is at stake," he said.

The 15-member council also voted on a Russian-drafted resolution on Thursday to renew the inquiry, but it failed after only garnering four votes in favor. Japan then proposed the council consider a 30-day extension.

As closed-door negotiations got under way on the Japanese text earlier on Friday, Russia told its counterparts that it could not accept the draft, did not want the body to show false unity and did not want to waste everyone's time, said council diplomats, speaking on condition of anonymity.

The U.S. State Department on Friday urged Russia to support the Japanese draft. White House Press secretary Sarah Huckabee Sanders said of Russia on Friday: "We do hope that moving forward they want to get on board and work with us on this."

A resolution needs nine votes in favor and no vetoes by the United States, France, Russia, Britain or China to be adopted.

While Russia agreed to the 2015 creation of the inquiry, it has consistently questioned its findings, which also concluded that the Syrian government used chlorine as a weapon several times.

Russia has vetoed 10 resolutions on Syria, including blocking an initial U.S. bid on Oct. 24 to renew the JIM, saying it wanted to wait for the release two days later of the inquiry's report that said the Syrian government used sarin.

The April 4 sarin attack on Khan Sheikhoun that killed dozens of people prompted the United States to launch missiles on a Syrian air base. Syria agreed to destroy its chemical weapons in 2013 under a deal brokered by Russia and the United States.

(Reporting by Michelle Nichols; Editing by Phil Berlowitz and James Dalgleish)